Sensitivity-Tunable Terahertz Liquid/Gas Biosensor Based on Surface Plasmon Resonance with Dirac Semimetal.

In this paper, we study the sensitivity-tunable terahertz (THz) liquid/gas biosensor in a coupling prism-three-dimensional Dirac semimetal (3D DSM) multilayer structure. The high sensitivity of the biosensor originates from the sharp reflected peak caused by surface plasmon resonance (SPR) mode. This structure achieves the tunability of sensitivity due to the fact that the reflectance could be modulated by the Fermi energy of 3D DSM. Besides, it is found that the sensitivity curve depends heavily on the structural parameters of 3D DSM. After parameter optimization, we obtained sensitivity over 100°/RIU for liquid biosensor. We believe this simple structure provides a reference idea for realizing high sensitivity and a tunable biosensor device.

Change trend and gender differences in disability-free life expectancy among older adults in China, 2010-2020.

Objective: The goal of the present study was to investigate gender differences in disability-free life expectancy (DFLE) and DFLE/LE ratio among older adults in China; portray changing trend from 2010 to 2020; and discuss the implications for public policies. Methods: Mortality data and disability rate data were derived from the Sixth China Population Census in 2010 and the Seventh China Population Census in 2020. The study assessed disability status of older adults based on self-assessment health in the above censuses. Life table and Sullivan method were used to estimate LE, DFLE, and DFLE/LE ratio by gender. Results: DFLE increased from 19.33 to 21.78 years for 60-year-old males, while from 21.94 to 24.80 years for 60-year-old females, from 2010 to 2020, respectively. DFLE/LE ratio was 96.40% for 60-year-old males and 94.86% for 60-year-old females in 2010, while DFLE/LE ratio was 96.63% for 60-year-old males and 95.44% for 60-year-old females in 2020, respectively. In terms of gender differences in DFLE/LE ratio, men aged 60 are 1.19 percentage points higher than women at the same age; men aged 70 are 1.71 percentage points higher than women; men aged 80 are 2.87 percentage points higher than women. Conclusion: From 2010 to 2020, the DFLE of China's male and female older adults increased simultaneously with the increase of LE, and the DFLE/LE ratio also increased. However, the DFLE/LE ratio of female older adults is lower than that of male at the same age, and this gender difference is narrowing over the decade but has not yet been eliminated, especially the health disadvantage of female older adults among the oldest old age group (age 80 and above) is more prominent.

Fine-Scale Interactions between Leopard Cats and Their Potential Prey with Contrasting Diel Activities in a Livestock-Dominated Nature Reserve.

Habitat use and the temporal activities of wildlife can be largely modified by livestock encroachment. Therefore, identifying the potential impacts of livestock on the predator-prey interactions could provide essential information for wildlife conservation and management. From May to October 2017, we used camera trapping technology to investigate fine-scale spatiotemporal interactions in a predator-prey system with the leopard cat (Prionailurus bengalensis) as a common mesopredator, and its prey with contrasting activity patterns (i.e., nocturnal rats and diurnal squirrels) in a livestock-dominated nature reserve in Northern China. We found that the prey species showed different habitat preferences with the leopard cats. The nocturnal rats had strong positive effects on the site-use of the leopard cats, while the influence of livestock on the diurnal squirrels' site-use changed from strong positive effects to weak effects as the livestock disturbance increased. The temporal overlap between the leopard cats and the nocturnal rats was almost four times that of the leopard cats and the diurnal squirrels, regardless of the livestock disturbance. Our study demonstrated that the fine-scale spatiotemporal use patterns of the leopard cats were consistent and highly correlated with the nocturnal rats under livestock disturbance. We suggest that appropriate restrictions on livestock disturbance should be implemented by reserve managers to reduce the threat to wildlife and achieve multi-species coexistence.

Terahertz Biosensor Based on Mode Coupling between Defect Mode and Optical Tamm State with Dirac Semimetal.

Bulk Dirac semimetal (BDS) has emerged as a "3D graphene" material for the development of optical devices in the past few years. In this study, a BDS-based tunable highly sensitive terahertz (THz) biosensor is proposed by using a Dirac semimetal/Bragg reflector multilayer structure. The high sensitivity of the biosensor originates from the sharp Fano resonance peak caused by coupling the Optical Tamm State (OTS) mode and defect mode. Besides, the sensitivity of the proposed structure is sensitive to the Fermi energy of Dirac semimetal and the refractive index of the sensing medium. The maximum sensitivity of 1022°/RIU is obtained by selecting structural and material parameter appropriately, which has certain competitiveness compared to conventional surface plasmon resonance (SPR) sensors. From the standpoint of the fabrication facility and integration, we judged that the BDS-based layered structure has the potential application in biosensor field.